Stormbringer (thing)

In Nethack, Stormbringer is a handy weapon for the chaotic. (If you are not chaotic, its power will blast you every time you pick it up; this makes it less handy). Apart from being a resonably powerful artifact, its attack often drains hp from its victims, transferring them to its bearer. This is nice.

What is less nice is that it will often attack of its own will. Well, not quite. But here's what happens: Motion into a monster is considered an attack. So normally, before attacking a peaceful monster, the game asks you if you're sure. Wielding Stormbringer, you throw such caution to the winds. This can be very dangerous, even for a chaotic character.